Vacuum gauges such as ionization vacuum gauges and diaphragm vacuum gauges for measuring high vacuum or ultrahigh vacuum, high vacuum pumps, material for vacuum, or the like require calibration at the present position where they are actually used (in-situ calibration). The in-situ calibration is performed by measuring the degree of vacuum inside a vacuum container in which a gas of a reference flow rate is introduced, and there is proposed to use a standard conductance element (SCE) in order to introduce the gas of the reference flow rate into the vacuum container (for example, refer to Patent Literature 1).